U.S. patent application number 16/264734 was filed with the patent office on 2019-05-30 for alkali-free glass substrate, laminated substrate, and glass substrate production method.
This patent application is currently assigned to AGC INC.. The applicant listed for this patent is AGC INC.. Invention is credited to Shuhei NOMURA, Kazutaka ONO.
Application Number | 20190161388 16/264734 |
Document ID | / |
Family ID | 61073812 |
Filed Date | 2019-05-30 |
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United States Patent
Application |
20190161388 |
Kind Code |
A1 |
NOMURA; Shuhei ; et
al. |
May 30, 2019 |
ALKALI-FREE GLASS SUBSTRATE, LAMINATED SUBSTRATE, AND GLASS
SUBSTRATE PRODUCTION METHOD
Abstract
An alkali-free glass substrate which is a glass substrate
includes, as represented by molar percentage based on oxides, 0.1%
to 10% of ZnO. The alkali-free glass substrate has an average
coefficient of thermal expansion .alpha..sub.50/100 at 50 to
100.degree. C. of from 2.70 ppm/.degree. C. to 3.20 ppm/.degree.
C., an average coefficient of thermal expansion .alpha..sub.200/300
at 200 to 300.degree. C. of from 3.45 ppm/.degree. C. to 3.95
ppm/.degree. C., and a value .alpha..sub.200/300/.alpha..sub.50/100
obtained by dividing the average coefficient of thermal expansion
.alpha..sub.200/300 at 200 to 300.degree. C. by the average
coefficient of thermal expansion .alpha..sub.50/100 at 50 to
100.degree. C. of from 1.20 to 1.30.
Inventors: |
NOMURA; Shuhei; (Tokyo,
JP) ; ONO; Kazutaka; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AGC INC. |
Chiyoda-ku |
|
JP |
|
|
Assignee: |
AGC INC.
Chiyoda-ku
JP
|
Family ID: |
61073812 |
Appl. No.: |
16/264734 |
Filed: |
February 1, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2017/027112 |
Jul 26, 2017 |
|
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|
16264734 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C03B 17/064 20130101;
B32B 17/00 20130101; C03C 3/091 20130101; C03B 17/067 20130101;
C03B 25/087 20130101; C03C 3/093 20130101 |
International
Class: |
C03C 3/093 20060101
C03C003/093; B32B 17/00 20060101 B32B017/00; C03C 3/091 20060101
C03C003/091 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2016 |
JP |
2016-154683 |
Claims
1. An alkali-free glass substrate which is a glass substrate
comprising, as represented by molar percentage based on oxides,
0.1% to 10% of ZnO, and having an average coefficient of thermal
expansion .alpha..sub.50/100 at 50 to 100.degree. C. of from 2.70
ppm/.degree. C. to 3.20 ppm/.degree. C., an average coefficient of
thermal expansion .alpha..sub.200/300 at 200 to 300.degree. C. of
from 3.45 ppm/.degree. C. to 3.95 ppm/.degree. C., and a value
.alpha..sub.200/300/.alpha..sub.50/100 obtained by dividing the
average coefficient of thermal expansion .alpha..sub.200/300 at 200
to 300.degree. C. by the average coefficient of thermal expansion
.alpha..sub.50/100 at 50 to 100.degree. C. of from 1.20 to
1.30.
2. The alkali-free glass substrate according to claim 1, wherein
the average coefficient of thermal expansion .alpha..sub.200/300 at
200 to 300.degree. C. is from 3.55 ppm/.degree. C. to 3.85
ppm/.degree. C.
3. The alkali-free glass substrate according to claim 1, having the
following composition as represented by molar percentage based on
oxides: SiO.sub.2: from 50% to 75%, Al.sub.2O.sub.3: from 6% to
16%, B.sub.2O.sub.3: from 0% to 15%, MgO: from 0% to 15%, CaO: from
0% to 13%, SrO: from 1% to 11%, BaO: from 0% to 9.5%, and
4. The alkali-free glass substrate according to claim 1, having a
total content of MgO, CaO, SrO, BaO, and ZnO of 10% or more, and
satisfying a relation of (content of
Al.sub.2O.sub.3).gtoreq.(content of MgO).
5. The alkali-free glass substrate according to claim 1, having an
average coefficient of thermal expansion .alpha..sub.100/200 at 100
to 200.degree. C. of from 3.13 ppm/.degree. C. to 3.63 ppm/.degree.
C.
6. The alkali-free glass substrate according to claim 1, having a
content of Fe.sub.2O.sub.3 of 200 ppm or less as represented by
mass ppm based on oxides.
7. The alkali-free glass substrate according to claim 1, having a
Young's modulus of 76 GPa or more.
8. The alkali-free glass substrate according to claim 1, which is
used for at least either one of a support substrate for
semiconductor production process and a cover glass.
9. The alkali-free glass substrate according to claim 1, having a
thickness of 1.0 mm or less.
10. The alkali-free glass substrate according to claim 1, having an
area of one main surface of 0.03 m.sup.2 or more.
11. The alkali-free glass substrate according to claim 1, having a
density of defects with a size of 0.5 .mu.m or more and 1 mm or
less contained in the glass substrate of 1 defect/cm.sup.2 or
less.
12. The alkali-free glass substrate according to claim 1, which
satisfies: 0.0177.times.(content of
SiO.sub.2)-0.0173.times.(content of
Al.sub.2O.sub.3)+0.0377.times.(content of
B.sub.2O.sub.3)+0.0771.times.(content of MgO)+0.1543.times.(content
of CaO)+0.1808.times.(content of SrO)+0.2082.times.(content of
BaO)+0.0396.times.(content of ZnO)+0.0344.times.(12.3+log.sub.10
60-log.sub.10 .eta.) is from 2.70 to 3.20, 0.0181.times.(content of
SiO.sub.2)+0.0004.times.(content of
Al.sub.2O.sub.3)+0.0387.times.(content of
B.sub.2O.sub.3)+0.0913.times.(content of MgO)+0.1621.times.(content
of CaO)+0.1900.times.(content of SrO)+0.2180.times.(content of
BaO)+0.0424.times.(content of ZnO)+0.0391.times.(12.3+log.sub.10
60-log.sub.10 .eta.) is 3.13 to 3.63, 0.0177.times.(content of
SiO.sub.2)+0.0195.times.(content of
Al.sub.2O.sub.3)+0.0323.times.(content of
B.sub.2O.sub.3)+0.1015.times.(content of MgO)+0.1686.times.(content
of CaO)+0.1990.times.(content of SrO)+0.2179.times.(content of
BaO)+0.0493.times.(content of ZnO)+0.0312.times.(12.3+log.sub.10
60-log.sub.10 .eta.) is 3.45 to 3.95, and 00.0111.times.(content of
SiO.sub.2)+0.0250.times.(content of
Al.sub.2O.sub.3)+0.0078.times.(content of
B.sub.2O.sub.3)+0.0144.times.(content of MgO)+0.0053.times.(content
of CaO)+0.0052.times.(content of SrO)+0.0013.times.(content of
BaO)+0.0121.times.(content of ZnO)-0.0041.times.(12.3+log.sub.10
60-log.sub.10 .eta.) is 1.20 to 1.30, wherein the contents of
SiO.sub.2, Al.sub.2O.sub.3, B.sub.2O.sub.3, MgO, CaO, SrO, BaO, and
ZnO are contents contained in a obtained glass as represented by
molar percentage based on oxides, and .eta. is a fictive viscosity
(unit: dPas).
13. A laminated substrate comprising the alkali-free glass
substrate according to claim 1 and a silicon substrate stacked
thereon.
14. A method for manufacturing an alkali-free glass substrate
comprising: a melting step of heating glass raw materials to obtain
a molten glass; a forming step of forming the molten glass into a
sheet-like shape to obtain a glass ribbon; and a slow cooling step
of gradually cooling the glass ribbon to a room temperature state,
wherein an obtained glass substrate has the following composition
as represented by molar percentage based on oxides: SiO.sub.2: from
50% to 75%, Al.sub.2O.sub.3: from 6% to 16%, B.sub.2O.sub.3: from
0% to 15%, MgO: from 0% to 15%, CaO: from 0% to 13%, SrO: from 0%
to 11%, BaO: from 0% to 9.5%, and ZnO: from 0.1% to 10%, and the
composition of the obtained glass substrate and an average cooling
rate R (unit: .degree. C./min) from a temperature at which the
viscosity of the glass ribbon becomes 10.sup.13 dPas to a
temperature at which the viscosity becomes 10.sup.14.5 dPas in the
slow cooling step satisfy the following conditions (1), (2), (3),
and (4): 0.0177.times.(content of SiO.sub.2)-0.0173.times.(content
of Al.sub.2O.sub.3)+0.0377.times.(content of
B.sub.2O.sub.3)+0.0771.times.(content of MgO)+0.1543.times.(content
of CaO)+0.1808.times.(content of SrO)+0.2082.times.(content of
BaO)+0.0396.times.(content of ZnO)+0.0344.times.log.sub.10 R is
from 2.70 to 3.20 Condition (1): 0.0181.times.(content of
SiO.sub.2)+0.0004.times.(content of
Al.sub.2O.sub.3)+0.0387.times.(content of
B.sub.2O.sub.3)+0.0913.times.(content of MgO)+0.1621.times.(content
of CaO)+0.1900.times.(content of SrO)+0.2180.times.(content of
BaO)+0.0424.times.(content of ZnO)+0.0391.times.log.sub.10 R is
3.13 to 3.63 Condition (2): 0.0177.times.(content of
SiO.sub.2)+0.0195.times.(content of
Al.sub.2O.sub.3)+0.0323.times.(content of
B.sub.2O.sub.3)+0.1015.times.(content of MgO)+0.1686.times.(content
of CaO)+0.1990.times.(content of SrO)+0.2179.times.(content of
BaO)+0.0493.times.(content of ZnO)+0.0312.times.log.sub.10 R is
3.45 to 3.95 Condition (3): 0.0111.times.(content of
SiO.sub.2)+0.0250.times.(content of
Al.sub.2O.sub.3)+0.0078.times.(content of
B.sub.2O.sub.3)+0.0144.times.(content of MgO)+0.0053.times.(content
of CaO)+0.0052.times.(content of SrO)+0.0013.times.(content of
BaO)+0.0121.times.(content of ZnO)-0.0041.times.log.sub.10 R is
1.20 to 1.30, Condition (4): wherein in the conditions (1) to (4),
the contents of SiO.sub.2, Al.sub.2O.sub.3, B.sub.2O.sub.3, MgO,
CaO, SrO, BaO, and ZnO are contents contained in a obtained glass
as represented by molar percentage based on oxides.
15. The method for manufacturing an alkali-free glass substrate
according to claim 14, wherein the molten glass is formed into a
sheet-like shape by a fusion process or a press forming process in
the forming step.
Description
TECHNICAL FIELD
[0001] The present invention relates to an alkali-free glass
substrate, a laminated substrate, and a glass substrate production
method.
[0002] As for an image sensor such as chip size package (CSP), a
system of protecting a silicon substrate by laminating a glass
substrate thereon is known. A glass for silicon pedestal, in which
the elongation percentage by thermal expansion is approximated to
the elongation percentage by thermal expansion of the silicon
substrate to be bonded with the glass is proposed (for example, see
Patent Document 1).
[0003] Until now in the semiconductor fabrication process, each of
a silicon substrate and a glass substrate is cut in the wafer
state, and the silicon substrate and the glass substrate are then
laminated together and subjected to a series of fabrication steps,
such as die bonding, wire bonding and molding. In recent years,
fabrication by a wafer-level packaging technique has the spotlight
as a next-generation CSP technique, in which a silicon substrate
and a glass substrate are laminated together in the wafer state,
subjected to fabrication steps, and then cut.
[0004] A heat treatment step is required for laminating together
the silicon substrate and the glass substrate. In the heat
treatment step, the temperature of a laminated substrate obtained
by laminating together the silicon substrate and the glass
substrate at a temperature of, for example, 200 to 400.degree. C.
is lowered to room temperature. At this time, if there is a
difference in the coefficient of thermal expansion between the
silicon substrate and the glass substrate, a large residual strain
(residual deformation) is caused to occur in the silicon substrate
due to a difference in coefficient of thermal expansion.
[0005] In the wafer-level packaging technique, the silicone
substrate and the glass substrate are laminated together in the
wafer state and therefore, even if the difference in coefficient of
thermal expansion is at a level heretofore not posed a problem, a
residual strain is readily generated in the silicon substrate.
PRIOR ART LITERATURE
Patent Document
[0006] Patent Document 1: Japanese Patent No. 3,153,710
[0007] Patent Document 1 has proposed glass for silicon pedestal,
characterized in that the ratio .alpha..sub.1/.alpha..sub.2 of the
elongation percentage .alpha..sub.1 by thermal expansion of the
glass and the elongation percentage .alpha..sub.2 by thermal
expansion of the silicon base material to be bonded with the glass
is from 0.8 to 1.2. However, as regards the glass of Examples
disclosed in Patent Document 1, its match in coefficient of thermal
expansion with that of the silicon substrate is insufficient, and
the wafer-level packaging technique is likely to accompany
generation of a residual strain in the silicone substrate.
[0008] Accordingly, one embodiment of the present invention
provides a glass substrate and a method for manufacturing a glass
substrate, in which in the heat treatment step of laminating
together a silicon substrate and a glass substrate, the residual
strain generated in the silicon substrate is small. Another
embodiment of the present invention provides a laminated substrate
including the glass substrate.
Means for Solving the Problems
[0009] The present inventors have found that when the composition
of the glass, coefficient of thermal expansion thereof, and
coefficient of thermal expansion of single-crystal silicon are set
to specific ranges, a glass substrate in which the coefficient of
thermal expansion matches that of the silicon substrate is
obtained. The present invention has been accomplished based on this
finding.
[0010] A glass substrate of one embodiment of the present invention
is an alkali-free glass substrate which includes, as represented by
molar percentage based on oxides,
[0011] 0.1% to 10% of ZnO,
[0012] and has an average coefficient of thermal expansion
.alpha..sub.50/100 at 50 to 100.degree. C. of from 2.70
ppm/.degree. C. to 3.20 ppm/.degree. C.,
[0013] an average coefficient of thermal expansion
.alpha..sub.200/300 at 200 to 300.degree. C. of from 3.45
ppm/.degree. C. to 3.95 ppm/.degree. C., and
[0014] a value .alpha..sub.200/300/.alpha..sub.50/100 obtained by
dividing the average coefficient of thermal expansion
.alpha..sub.200/300 at 200 to 300.degree. C. by the average
coefficient of thermal expansion .alpha..sub.50/100 at 50 to
100.degree. C. is from 1.20 to 1.30.
[0015] A laminated substrate of one embodiment of the present
invention includes the glass substrate and a silicon substrate
stacked thereon.
[0016] A method for manufacturing an alkali-free glass substrate of
one embodiment of the present invention includes,
[0017] a melting step of heating glass raw materials to obtain a
molten glass,
[0018] a forming step of forming the molten glass into a sheet-like
shape to obtain a glass ribbon, and
[0019] a slow cooling step of gradually cooling the glass ribbon to
a room temperature state. In the method, the obtained glass
substrate has the following composition as represented by molar
percentage based on oxides:
[0020] SiO.sub.2: from 50% to 75%,
[0021] Al.sub.2O.sub.3: from 6% to 16%,
[0022] B.sub.2O.sub.3: from 0% to 15%,
[0023] MgO: from 0% to 15%,
[0024] CaO: from 0% to 13%,
[0025] SrO: from 0% to 11%,
[0026] BaO: from 0% to 9.5%, and
[0027] ZnO: from 0.1% to 10%.
[0028] In the method, the composition of the obtained glass
substrate and an average cooling rate R (unit: .degree. C./min)
from a temperature at which the viscosity of the glass ribbon
becomes 10.sup.13 dPas to a temperature at which the viscosity
becomes 10.sup.14.5 dPas in the slow cooling step satisfy the
following conditions (1), (2), (3) and (4):
0.0177.times.(content of SiO.sub.2)-0.0173.times.(content of
Al.sub.2O.sub.3)+0.0377.times.(content of
B.sub.2O.sub.3)+0.0771.times.(content of MgO)+0.1543.times.(content
of CaO)+0.1808.times.(content of SrO)+0.2082.times.(content of
BaO)+0.0396.times.(content of ZnO)+0.0344.times.log.sub.10 R is
from 2.70 to 3.20 Condition (1):
0.0181.times.(content of SiO.sub.2)+0.0004.times.(content of
Al.sub.2O.sub.3)+0.0387.times.(content of
B.sub.2O.sub.3)+0.0913.times.(content of MgO)+0.1621.times.(content
of CaO)+0.1900.times.(content of SrO)+0.2180.times.(content of
BaO)+0.0424.times.(content of ZnO)+0.0391.times.log.sub.10 R is
3.13 to 3.63 Condition (2):
0.0177.times.(content of SiO.sub.2)+0.0195.times.(content of
Al.sub.2O.sub.3)+0.0323.times.(content of
B.sub.2O.sub.3)+0.1015.times.(content of MgO)+0.1686.times.(content
of CaO)+0.1990.times.(content of SrO)+0.2179.times.(content of
BaO)+0.0493.times.(content of ZnO)+0.0312.times.log.sub.10 R is
3.45 to 3.95 Condition (3):
0.0111.times.(content of SiO.sub.2)+0.0250.times.(content of
Al.sub.2O.sub.3)+0.0078.times.(content of
B.sub.2O.sub.3)+0.0144.times.(content of MgO)+0.0053.times.(content
of CaO)+0.0052.times.(content of SrO)+0.0013.times.(content of
BaO)+0.0121.times.(content of ZnO)-0.0041.times.log.sub.10 R is
1.20 to 1.30 Condition (4):
[In the conditions (1) to (4), the contents of SiO.sub.2,
Al.sub.2O.sub.3, B.sub.2O.sub.3, MgO, CaO, SrO, BaO, and ZnO are
contents as represented by molar percentage based on oxides
contained in a obtained glass.]
Advantage of the Invention
[0029] One embodiment of the present invention can provide a glass
substrate and a method for manufacturing a glass substrate in which
the coefficient of thermal expansion of the glass substrate matches
that of the silicon substrate, the residual strain generated in the
silicon substrate is small in the heat treatment step of laminating
together a silicon substrate and a glass substrate, and
manufacturing property is excellent. Further, one embodiment of the
present invention can provide a laminated substrate including the
glass substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1A and FIG. 1B show a glass substrate according to one
embodiment of the present invention, which is laminated together
with a silicon substrate; FIG. 1A is a cross-sectional view before
lamination together; and FIG. 1B is a cross-sectional view after
lamination together.
MODE FOR CARRYING OUT THE INVENTION
[0031] One embodiment of the present invention is described
below.
[0032] In the present description, unless otherwise indicated, the
content of each component in the glass substrate and a
manufacturing method thereof is as represented by molar percentage
based on oxides.
[0033] Furthermore, in the present description, unless otherwise
indicated, the "-" indicating a numerical value range is used in
the sense of including the numerical values before and after that
as a lower limit value and an upper limit value
[0034] FIG. 1A and FIG. 1B show a glass substrate according to one
embodiment of the present invention, which is laminated together
with a silicon substrate. The glass substrate G1 obtained by the
present invention illustrated in FIG. 1A and a silicon substrate 10
sandwich a resin 20 and are laminated together, for example, at a
temperature of 200 to 400.degree. C. to obtain a laminated
substrate 30 illustrated in FIG. 1B. As the silicon substrate 10,
for example, a full-sized wafer (for example, a wafer containing
silicon as a component, such as silicon wafer) is used. The silicon
substrate 10 may be a wafer formed thereon a device, or a substrate
in which a chip (for example, silicon chip), in which a device is
cut out from a wafer, is molded with a resin. The resin 20 may be
any resin as long as it can withstand the temperature of 200 to
400.degree. C.
[0035] In the glass substrate of the present invention, the average
coefficient of thermal expansion .alpha..sub.50/100 at 50 to
100.degree. C. is 2.70 ppm/.degree. C. or more, preferably 2.80
ppm/.degree. C. or more, more preferably 2.90 ppm/.degree. C. or
more, still more preferably 2.91 ppm/.degree. C. or more, and
especially preferably 2.92 ppm/.degree. C. or more. In addition,
.alpha..sub.50/100 is 3.20 ppm/.degree. C. or less, preferably 3.10
ppm/.degree. C. or less, more preferably 3.00 ppm/.degree. C. or
less, still more preferably 2.96 ppm/.degree. C. or less, and
especially preferably 2.94 ppm/.degree. C. or less. When
.alpha..sub.50/100 is in the range above, the difference in
coefficient of thermal expansion from the silicon substrate can be
reduced.
[0036] Here, the average coefficient of thermal expansion
.alpha..sub.50/100 at 50 to 100.degree. C. is an average
coefficient of thermal expansion as measured by the method
prescribed in JIS R3102 (1995), in which the temperature range when
measuring the coefficient of thermal expansion is from 50 to
100.degree. C.
[0037] In the glass substrate of the present invention, an average
coefficient of thermal expansion .alpha..sub.100/200 at 100 to
200.degree. C. is preferably 3.13 ppm/.degree. C. or more, more
preferably 3.23 ppm/.degree. C. or more, still more preferably 3.33
ppm/.degree. C. or more, especially preferably 3.34 ppm/.degree. C.
or more, and most preferably 3.35 ppm/.degree. C. or more. In
addition, .alpha..sub.100/200 is preferably 3.63 ppm/.degree. C. or
less, more preferably 3.53 ppm/.degree. C. or less, still more
preferably 3.43 ppm/.degree. C. or less, especially preferably 3.41
ppm/.degree. C. or less, and most preferably 3.38 ppm/.degree. C.
or less. When .alpha..sub.100/200 is in the range above, the
difference in coefficient of thermal expansion from the silicon
substrate can be reduced.
[0038] Here, the average coefficient of thermal expansion
.alpha..sub.100/200 at 100 to 200.degree. C. is an average
coefficient of thermal expansion as measured by the method
prescribed in JIS R3102 (1995), in which the temperature range when
measuring the coefficient of thermal expansion is from 100 to
200.degree. C.
[0039] In the glass substrate of the present invention, the average
coefficient of thermal expansion .alpha..sub.200/300 at 200 to
300.degree. C. is 3.45 ppm/.degree. C. or more, preferably 3.55
ppm/.degree. C. or more, more preferably 3.65 ppm/.degree. C. or
more, especially preferably 3.66 ppm/.degree. C. or more, and most
preferably 3.68 ppm/.degree. C. or more. In addition,
.alpha..sub.200/300 is 3.95 ppm/.degree. C. or less, preferably
3.85 ppm/.degree. C. or less, more preferably 3.75 ppm/.degree. C.
or less, especially preferably 3.73 ppm/.degree. C. or less, and
most preferably 3.71 ppm/.degree. C. or less.
[0040] When .alpha..sub.200/300 is in the range above, the
difference in coefficient of thermal expansion from the silicon
substrate can be reduced. When .alpha..sub.200/300 is from 3.55
ppm/.degree. C. to 3.85 ppm/.degree. C., the difference in the
coefficient of thermal expansion from the silicon substrate can be
reduced enough and a failure due to the difference in the
coefficient of thermal expansion can be prevented.
[0041] Here, the average coefficient of thermal expansion
.alpha..sub.200/300 at 200 to 300.degree. C. is an average
coefficient of thermal expansion as measured by the method
prescribed in JIS R3102 (1995), in which the temperature range when
measuring the coefficient of thermal expansion is from 200 to
300.degree. C.
[0042] In the glass substrate of the present invention, the value
.alpha..sub.200/300/.alpha..sub.50/100 obtained by dividing the
average coefficient of thermal expansion .alpha..sub.200/300 at 200
to 300.degree. C. by the average coefficient of thermal expansion
.alpha..sub.50/100 at 50 to 100.degree. C. is 1.20 or more,
preferably 1.22 or more, and more preferably 1.24 or more. In
addition, .alpha..sub.200/300/+.sub.50/100 is 1.30 or less,
preferably 1.27 or less, and more preferably 1.26 or less. When
.alpha..sub.200/300/.alpha..sub.50/100 is in the range above, the
difference in the coefficient of thermal expansion from the silicon
substrate can be reduced.
[0043] In the glass substrate of the present invention, the
absolute value |.DELTA..alpha..sub.50/100| of the difference
between the average coefficient of thermal expansion
.alpha..sub.50/100 of the glass substrate and the average
coefficient of thermal expansion of single-crystal silicon at 50 to
100.degree. C., the absolute value |.DELTA..alpha..sub.100/200| of
the difference between the average coefficient of thermal expansion
.alpha..sub.100/200 of the glass substrate and the average
coefficient of thermal expansion of single-crystal silicon at 100
to 200.degree. C., and the absolute value
|.DELTA..alpha..sub.200/300| of the difference between the average
coefficient of thermal expansion .alpha..sub.200/300 of the glass
substrate and the average coefficient of thermal expansion of
single-crystal silicon at 200 to 300.degree. C. are preferably 0.16
ppm/.degree. C. or less, more preferably 0.15 ppm/.degree. C. or
less, still more preferably 0.12 ppm/.degree. C. or less.
[0044] When |.DELTA..alpha..sub.50/100|,
|.DELTA..alpha..sub.100/200| and |.DELTA..alpha..sub.200/300| are
0.16 ppm/.degree. C. or less respectively, the difference in the
coefficient of thermal expansion from the silicon substrate can be
reduced.
[0045] The glass substrate of one embodiment of the present
invention is an alkali-free glass substrate. In the alkali-free
glass substrate, the content of an alkali metal oxide is preferably
from 0% to 0.1%. The content of an alkali metal oxide is more
preferably 0.05% or less, still more preferably 0.02% or less, and
it is particularly preferable to contain substantially no alkali
metal oxide. When the content of an alkali metal oxide is 0.1% or
less, an alkali ion can hardly diffuse into the silicon substrate
in the heat treatment step of laminating together the silicon
substrate and the glass substrate.
[0046] Here, "contain substantially no alkali metal oxide" means
that an alkali metal oxide is not contained at all or an alkali
metal oxide may be contained as an impurity mixed unavoidably due
to manufacturing reason. The alkali metal oxide includes, for
example, Li.sub.2O, Na.sub.2O, and K.sub.2O.
[0047] In the glass substrate of one embodiment of the present
invention, the content of ZnO is, as represented by molar
percentage based on oxides, 0.1% or more, preferably 0.5% or more,
more preferably 1% or more, most preferably 2% or more. In order to
reduce the difference in the coefficient of thermal expansion from
the silicon substrate, it is preferable to reduce the proportion of
network modifier (NWM) such as MgO, CaO, SrO, BaO, and ZnO.
[0048] On the other hand, it is preferable to increase the
proportion of the network modifier in order that while the
viscosity during glass melting is reduced, the devitrification
temperature is lowered, facility load is reduced, and manufacturing
property is improved. The present inventors have found that, of the
network modifiers, ZnO can improve manufacturing property without
increasing the difference in the coefficient of thermal expansion
from the silicon substrate. When the content of ZnO is 0.1% or
more, the above-described effects can be fully obtained.
[0049] The content of ZnO is preferably 10% or less, more
preferably 9% or less, still more preferably 8% or less. When the
content of ZnO is 10% or less, crystallization due to ZnO can be
suppressed.
[0050] The glass substrate of one embodiment of the present
invention preferably has the following composition as represented
by molar percentage based on oxides:
[0051] SiO.sub.2: from 50% to 75%,
[0052] Al.sub.2O.sub.3: from 6% to 16%,
[0053] B.sub.2O.sub.3: from 0% to 15%,
[0054] MgO: from 0% to 15%,
[0055] CaO: from 0% to 13%,
[0056] SrO: from 0% to 11%, and
[0057] BaO: from 0% to 9.5%.
[0058] SiO.sub.2 is a component forming network of glass. The
content of SiO.sub.2 is preferably 50% or more, more preferably 55%
or more, still more preferably 60% or more, yet still more
preferably 65% or more. When the content of SiO.sub.2 is 50% or
more, the heat resistance, chemical durability and weather
resistance are improved. In addition, the content of SiO.sub.2 is
preferably 75% or less, more preferably 72% or less, still more
preferably 70% or less, yet still more preferably 67% or less. When
the content of SiO.sub.2 is 75% or less, the viscosity during glass
melting does not rise excessively, offering good meltability, and
the density increases.
[0059] The content of Al.sub.2O.sub.3 is preferably 6% or more,
preferably 8% or more, and more preferably 11% or more. When the
content of Al.sub.2O.sub.3 is 6% or more, the difference in
coefficient of thermal expansion from the silicon substrate is
reduced, and the weather resistance, heat resistance and chemical
durability are improved. In addition, the content of
Al.sub.2O.sub.3 is preferably 16% or less, more preferably 15% or
less, still more preferably 14% or less, yet still more preferably
13% or less. When the content of Al.sub.2O.sub.3 is 16% or less,
the viscosity during glass melting does not rise excessively,
offering good meltability, devitrification is less likely to occur,
and the Young's modulus can be reduced.
[0060] B.sub.2O.sub.3 is not an essential component, but when
contained, the viscosity during glass melting does not rise
excessively, offering good meltability, and devitrification is less
likely to occur. In the case of containing B.sub.2O.sub.3, the
content thereof is preferably 3% or more, and more preferably 4% or
more. The content of B.sub.2O.sub.3 is preferably 15% or less, more
preferably 12% or less, and still more preferably 6% or less. When
the content of B.sub.2O.sub.3 is 15% or less, the glass transition
temperature can be raised, and the Young's modulus is
increased.
[0061] MgO is not an essential component, but when contained, the
viscosity during glass melting does not rise excessively, offering
good meltability, the weather resistance is enhanced, and the
Young's modulus is increased. In the case of containing MgO, the
content thereof is preferably 2% or more, more preferably 3% or
more, and still more preferably 4% or more. The content of MgO is
preferably 15% or less, more preferably 9.5% or less, and still
more preferably 9% or less. When the content of MgO is 15% or less,
devitrification is less likely to occur.
[0062] CaO is not an essential component, but when contained, the
viscosity during glass melting does not rise excessively, offering
good meltability, and the weather resistance is enhanced. In the
case of containing CaO, the content thereof is preferably 0.5% or
more, more preferably 1% or more, and still more preferably 3% or
more. In addition, the content of CaO is preferably 13% or less,
more preferably 10% or less, still more preferably 9% or less, yet
still more preferably 8% or less. When the content of CaO is 13% or
less, devitrification is less likely to occur, and the Young's
modulus can be reduced.
[0063] SrO is not an essential component, but when contained, the
viscosity during glass melting does not rise excessively, offering
good meltability, and the weather resistance is enhanced. In the
case of containing SrO, the content thereof is preferably 0.5% or
more, more preferably 1% or more. In addition, the content of SrO
is preferably 11% or less, more preferably 9% or less, and still
more preferably 3% or less. When the content of SrO is 11% or less,
devitrification is less likely to occur.
[0064] BaO is not an essential component, but when contained, the
viscosity during glass melting does not rise excessively, offering
good meltability, the weather resistance is enhanced, and the
density can be increased. In the case of containing BaO, the
content thereof is preferably 0.5% or more, more preferably 1% or
more. The content of BaO is preferably 9.5% or less, more
preferably 8% or less, and still more preferably 3% or less. When
the content of BaO is 9.5% or less, devitrification is less likely
to occur.
[0065] In the glass substrate of one embodiment of the present
invention, the total content (RO) of MgO, CaO, SrO, BaO, and ZnO is
preferably 10% or more, more preferably 12% or more, still more
preferably 14% or more, and yet still more preferably 15% or
more.
[0066] When RO is 10% or more, while the viscosity during glass
melting is reduced, the devitrification temperature is lowered,
facility load is reduced, and manufacturing property can be
improved. In addition, RO is preferably 23% or less, more
preferably 21% or less, and still more preferably 19% or less. When
RO is 23% or less, the coefficient of thermal expansion can be
easily matched between the glass substrate and the silicon
substrate.
[0067] The composition of the glass substrate of one embodiment of
the present invention is measured with a commonly used composition
analyzer such as X-ray fluorescence analyzer (XRF), energy
dispersive X-ray analyzer attached to the scanning electron
microscope (SEM-EDX), and electron probe micro analyzer (EPMA).
[0068] The glass substrate of one embodiment of the present
invention preferably satisfies a relation of (content of
Al.sub.2O.sub.3).gtoreq.(content of MgO). When the relation of
(content of Al.sub.2O.sub.3).gtoreq.(content of MgO) is satisfied,
the coefficient of thermal expansion can be easily matched between
the glass substrate and the silicon substrate, and the residual
strain generated in the silicon substrate in the heat treatment
step of laminating together the silicon substrate and the glass
substrate is small. In the glass substrate of one embodiment of the
present invention, it is preferable that RO is 10% or more and the
relation of (content of Al.sub.2O.sub.3).gtoreq.(content of MgO) is
satisfied.
[0069] In the case of using the glass substrate of one embodiment
of the present invention as a cover glass of CMOS sensor, in order
to absorb little visible light, the content of Fe.sub.2O.sub.3 is,
as represented by mass ppm based on oxides, preferably 200 ppm or
less, more preferably 150 ppm or less, still more preferably 100
ppm or less, yet still more preferably 50 ppm or less.
[0070] In order to increase the thermal conductivity and improve
the meltability, the glass substrate of one embodiment of the
present invention preferably contains, as represented by mass ppm
based on oxides, more than 200 ppm and 1,000 ppm or less of
Fe.sub.2O.sub.3. When the content of Fe.sub.2O.sub.3 is more than
200 ppm, it becomes possible to increase the thermal conductivity
of the glass substrate and improve the meltability. When the
content of Fe.sub.2O.sub.3 is 1,000 ppm or less, absorption of
visible light is not enhanced excessively.
[0071] The content of Fe.sub.2O.sub.3 is more preferably 300 ppm or
more, still more preferably 400 ppm or more, yet still more
preferably 500 ppm or more. The content of Fe.sub.2O.sub.3 is more
preferably 800 ppm or less, still more preferably 700 ppm or less,
yet still more preferably 600 ppm or less.
[0072] In the glass substrate of one embodiment of the present
invention, for example, SnO.sub.2, SO.sub.3, Cl, or F may be
contained as a refining agent.
[0073] In the glass substrate of one embodiment of the present
invention, for example, Li.sub.2O, WO.sub.3, Nb.sub.2O.sub.5,
V.sub.2O.sub.5, Bi.sub.2O.sub.3, MoO.sub.3, P.sub.2O.sub.5,
Ga.sub.2O.sub.3, I.sub.2O.sub.5, In.sub.2O.sub.5, or
Ge.sub.2O.sub.5 may be contained so as to improve the weather
resistance, meltability, devitrification property, ultraviolet
shielding, infrared shielding, ultraviolet transmission, infrared
transmission, etc.
[0074] In the glass substrate of one embodiment of the present
invention, the glass may contain ZrO.sub.2, Y.sub.2O.sub.3,
La.sub.2O.sub.3, TiO.sub.2, and SnO.sub.2 in a combined amount of
2% or less, preferably 1% or less, more preferably 0.5% or less, so
as to enhance the chemical durability of glass. Of these,
Y.sub.2O.sub.3, La.sub.2O.sub.3, and TiO.sub.2 contribute to
improvement of the Young's modulus of the glass.
[0075] In the glass substrate of one embodiment of the present
invention, considering an environmental load, it is preferred that
As.sub.2O.sub.3 and Sb.sub.2O.sub.3 are not substantially
contained.
[0076] In the glass substrate of one embodiment of the present
invention, the Young's modulus is 76.0 GPa or more, preferably 78
GPa or more, more preferably 80 GPa or more, still more preferably
82 GPa or more. When the Young's modulus is 76.0 GPa or more,
cracks and warpage during the slow cooling step in manufacturing
glass substrate can be prevented. In addition, damage due to
contact with a silicon substrate, a peripheral member, etc. can be
prevented.
[0077] The Young's modulus is preferably 100 GPa or less, more
preferably 90 GPa or less, and still more preferably 87 GPa or
less. When the Young's modulus is 100 GPa or less, the glass is
prevented from getting brittle and chipping during cutting the
glass substrate or dicing is suppressed.
[0078] In the glass substrate of one embodiment of the present
invention, the thickness thereof is preferably 1.0 mm or less, more
preferably 0.8 mm or less, still more preferably 0.7 mm or less,
yet still more preferably 0.5 mm or less. When the thickness is 1.0
mm or less, an image sensor can be made compact.
[0079] In addition, the thickness is preferably 0.1 mm or more,
more preferably 0.2 mm or more, still more preferably 0.3 mm or
more. When the thickness is 0.1 mm or more, damage due to contact
with a silicon substrate, a peripheral member, etc. can be
prevented. Furthermore, self-weight deflection of the glass
substrate can be suppressed.
[0080] In the glass substrate of one embodiment of the present
invention, the area of one main surface is preferably 0.03 m.sup.2
or more, more preferably 0.04 m.sup.2 or more, still more
preferably 0.05 m.sup.2 or more. When the area is 0.03 m.sup.2 or
more, a large-area silicon substrate can be used, and a large
number of image sensors can be manufactured from one sheet of the
laminated substrate.
[0081] The area of one main surface is preferably 0.1 m.sup.2 or
less. When the area is 0.1 m.sup.2 or less, the glass substrate can
be easily treated, and damage due to contact with a silicon
substrate, a peripheral member, etc. can be prevented. The area of
one main surface is more preferably 0.08 m.sup.2 or less, still
more preferably 0.06 m.sup.2 or less.
[0082] In the glass substrate of one embodiment of the present
invention, the density of defects contained in the glass substrate
is preferably 1 defect/cm.sup.2 or less, preferably 0.1
defect/cm.sup.2 or less, more preferably 0.01 defect/cm.sup.2 or
less. The defect contained in the glass substrate includes a
bubble, a scratch, a metal impurity such as platinum, an unmelted
raw material, etc. existing on the surface of or inside the glass
substrate and indicates a defect having a size of 1 mm or less and
0.5 .mu.m or more. When the defect is larger than 1 mm, it can be
easily discriminated with an eye, and a substrate having a defect
can be easily excluded. When the defect is smaller than 0.5 .mu.m,
the defect is sufficiently small and less likely to affect the
device properties even if the glass substrate is applied as a cover
glass of CMOS sensor or LCOS.
[0083] In the conventional semiconductor fabrication process, the
fabrication process is performed after cutting the glass substrate
and therefore, in the case of containing a defect in a glass
substrate, the substrate having a defect can be excluded in an
early stage of the fabrication process. On the other hand, in the
wafer-level packaging, since the laminated substrate is singulated
at the end of the fabrication process, in the case of containing a
defect in a glass substrate, the glass substrate having a defect
can be excluded at the end of the fabrication process. Thus, in the
wafer-level packaging, if the density of defects in the glass
substrate is increased, the cost rises significantly and therefore,
defect control at high level is required.
[0084] The shape of the glass substrate of one embodiment of the
present invention is not particularly limited and may be a circle,
an ellipse, and a rectangle. In order to make the shape of the
glass substrate conform to the shape of the silicon substrate, an
end of the glass substrate may be formed with a notch or
orientation flat. In the case where the glass substrate is
circular, part of the outer periphery of the glass substrate may be
a straight line.
[0085] In the glass substrate of one embodiment of the present
invention, the value represented by the following formula (1) is
preferably 2.70 or more, more preferably 2.80 or more, still more
preferably 2.90 or more, yet still more preferably 2.91 or more,
most preferably 2.92 or more. The value represented by the
following formula (1) is preferably 3.20 or less, more preferably
3.10 or less, still more preferably 3.00 or less, yet still more
preferably 2.96 or less, most preferably 2.94 or less.
0.0177.times.(content of SiO.sub.2)-0.0173.times.(content of
Al.sub.2O.sub.3)+0.0377.times.(content of
B.sub.2O.sub.3)+0.0771.times.(content of MgO)+0.1543.times.(content
of CaO)+0.1808.times.(content of SrO)+0.2082.times.(content of
BaO)+0.0396.times.(content of ZnO)+0.0344.times.(12.3+log.sub.10
60-log.sub.10 .eta.) Formula (1):
[0086] In the glass substrate of one embodiment of the present
invention, the value represented by the following formula (2) is
preferably 3.13 or more, more preferably 3.23 or more, still more
preferably 3.33 or more, yet still more preferably 3.34 or more,
most preferably 3.35 or more. The value represented by the
following formula (2) is preferably 3.63 or less, more preferably
3.53 or less, still more preferably 3.43 or less, yet still more
preferably 3.41 or less, most preferably 3.38 or less.
0.0181.times.(content of SiO.sub.2)+0.0004.times.(content of
Al.sub.2O.sub.3)+0.0387.times.(content of
B.sub.2O.sub.3)+0.0913.times.(content of MgO)+0.1621.times.(content
of CaO)+0.1900.times.(content of SrO)+0.2180.times.(content of
BaO)+0.0424.times.(content of ZnO)+0.0391.times.(12.3+log.sub.10
60-log.sub.10 .eta.) Formula (2):
[0087] In the glass substrate of one embodiment of the present
invention, the value represented by the following formula (3) is
preferably 3.45 or more, more preferably 3.55 or more, still more
preferably 3.65 or more, yet still more preferably 3.66 or more,
most preferably 3.68 or more. The value represented by the
following formula (3) is preferably 3.95 or less, more preferably
3.85 or less, still more preferably 3.73 or less, yet still more
preferably 3.65 or less, most preferably 3.71 or less.
0.0177.times.(content of SiO.sub.2)+0.0195.times.(content of
Al.sub.2O.sub.3)+0.0323.times.(content of
B.sub.2O.sub.3)+0.1015.times.(content of MgO)+0.1686.times.(content
of CaO)+0.1990.times.(content of SrO)+0.2179.times.(content of
BaO)+0.0493.times.(content of ZnO)+0.0312.times.(12.3+log.sub.10
60-log.sub.10 .eta.) Formula (3):
[0088] In the glass substrate of one embodiment of the present
invention, the value represented by the following formula (4) is
preferably 1.20 or more, more preferably 1.24 or more. The value
represented by the following formula (4) is preferably 1.30 or
less, more preferably 1.27 or less, still more preferably 1.26 or
less.
0.0111.times.(content of SiO.sub.2)+0.0250.times.(content of
Al.sub.2O.sub.3)+0.0078.times.(content of
B.sub.2O.sub.3)+0.0144.times.(content of MgO)+0.0053.times.(content
of CaO)+0.0052.times.(content of SrO)+0.0013.times.(content of
BaO)+0.0121.times.(content of ZnO)-0.0041.times.(12.3+log.sub.10
60-log.sub.10 .eta.) Formula (4):
[0089] In the glass substrate of one embodiment of the present
invention, it is preferable that the value represented by the
following formula (1) is from 2.70 to 3.20, the value represented
by the following formula (2) is from 3.13 to 3.63, the value
represented by the following formula (3) is from 3.45 to 3.95, and
the value represented by the following formula (4) is from 1.20 to
1.30.
[0090] The contents of SiO.sub.2, Al.sub.2O.sub.3, B.sub.2O.sub.3,
MgO, CaO, SrO, BaO, and ZnO are contents of each component
contained in a obtained glass. .eta. is the fictive viscosity
(unit: dPa.$).
[0091] The fictive viscosity (.eta.) of glass can be calculated
according to the following formula [G. W. Scherer, "Relaxation in
Glass and Composites", Wiley, New York (1986), p. 159]:
log.sub.10 .eta.=12.3-log.sub.10|q|
[0092] The unit of .eta. is dPas, q is an estimated cooling rate,
and the unit thereof is .degree. C./s. The estimated cooling rate q
is determined from the glass substrate by the following method. A
plurality of glass plate pieces are cut out from one sheet of the
glass substrate having a thickness of 1 mm or less. For example, a
piece of 1 cm square is cut out as the glass plate piece. The
plurality of glass plate pieces cut out are heat-treated and cooled
at various cooling rates V, and physical property values of each
individual glass plate piece are measured. The cooling start
temperature is preferably a sufficiently high temperature not to be
affected by the cooling rate and, typically, is preferably on the
order of Tg+50.degree. C. to +150.degree. C.
[0093] The physical property values measured are not particularly
limited, but a density, physical property values closely related to
the density (for example, a refractive index), etc. are preferred.
A calibration curve A is prepared by plotting the cooling rate
(log.sub.10 V) on the x-axis and plotting the physical property
values of each individual heat-treated glass plate piece on the
y-axis. From the physical property values of each individual glass
plate piece not having been heat-treated, the estimated cooling
rate q of the glass substrate is determined using the prepared
calibration curve A.
[0094] In the glass substrate one embodiment of the present
invention, the weight reduction amount relative to an aqueous
hydrofluoric acid solution (HF) (hereinafter, sometimes referred to
as HF weight reduction amount) is preferably 0.05 (mg/cm.sup.2)/min
or more, more preferably 0.07 (mg/cm.sup.2)/min or more, still more
preferably 0.09 (mg/cm.sup.2)/min or more, yet still more
preferably 0.11 (mg/cm.sup.2)/min or more. HF weight reduction
amount is preferably 0.20 (mg/cm.sup.2)/min or less, more
preferably 0.18 (mg/cm.sup.2)/min or less, still more preferably
0.16 (mg/cm.sup.2)/min or less, yet still more preferably 0.14
(mg/cm.sup.2)/min or less. Here, the HF weight reduction amount is
a reduction amount per unit area and unit time [(mg/cm.sup.2)/min]
when immersing the glass substrate in an aqueous 5 mass %
hydrofluoric acid solution at 25.degree. C.
[0095] The glass substrate of one embodiment of the present
invention is sometimes incorporated as part of a device directly
after lamination together with the silicon substrate. For example,
the glass substrate is incorporated as a cover glass into a device.
In such a case, the glass substrate is preferably subjected to
slimming so as to make the device compact. Accordingly, the glass
substrate in one embodiment of the present invention preferably has
a higher slimming rate. An HF weight reduction amount can be used
as an indicator of the slimming rate of the glass substrate.
[0096] When the HF weight reduction amount is 0.05
(mg/cm.sup.2)/min or more, good productivity is favorably obtained
in the slimming step. When the HF weight reduction amount is 0.20
(mg/cm.sup.2)/min or less, a failure such that possible unevenness
of the etching depth generated in the glass substrate in the
slimming step impairs the smoothness of the glass substrate surface
can be advantageously prevented.
[0097] The glass substrate of the present invention can be applied
as a cover glass of a projection-use display device, for example,
LCOS. In such a case, if the photoelastic constant of the glass
substrate is high, the glass substrate has birefringence due to a
stress generated in a device packaging step or in use of the
device. As a result, a color change may be caused in light having
entered the device, leading to an image quality failure such as
color unevenness.
[0098] In order to prevent such an image quality failure, in the
glass substrate of one embodiment of the present invention, the
photoelastic constant is preferably 31 nm/(MPacm) or less, more
preferably 30.5 nm/(MPacm) or less, still more preferably 30
nm/(MPacm) or less, yet still more preferably 29.5 nm/(MPacm) or
less.
[0099] In addition, in the glass substrate of one embodiment of the
present invention, an .alpha.-ray emission amount is preferably 0.5
C/cm.sup.2h or less, more preferably 0.3 C/cm.sup.2h or less, still
more preferably 0.1 C/cm.sup.2h or less, and most preferably 0.05
C/cm.sup.2h or less. The unit C means the number of counts.
[0100] For example, the glass substrate of one embodiment of the
present invention is applied to a cover glass of a device such as
image sensor. In this case, when an .alpha.-ray generated from the
glass substrate enters a device such as image sensor, a
hole-electron pair may be induced by the energy of .alpha.-ray,
giving rise to occurrence of a soft error that is a ray effect of
instantaneously producing a bright spot or a white spot on an
image.
[0101] Therefore, use of a glass substrate with a small .alpha.-ray
emission amount is likely to prevent such a trouble. When a
high-purity raw material having a small radioactive isotope content
and a small .alpha.-ray emission amount is used as a raw material
of the glass substrate, the .alpha.-ray emission amount can be
decreased.
[0102] Furthermore, in a melting/refining step of glass, when a
radioactive isotope is prevented from getting mixed in with the
molten glass from a furnace material, etc. of a glass manufacturing
facility, the .alpha.-ray emission amount can be effectively
decreased. The ".alpha.-ray emission amount" can be measured by a
gas flow proportional counter measuring apparatus, etc.
[0103] The laminated substrate of one embodiment of the present
invention is formed through stacking of the above-described glass
substrate and a silicon substrate. Since the difference in
coefficient of thermal expansion between the silicon substrate and
the glass substrate is small, the residual strain generated in the
silicon substrate in the heat treatment step of laminating together
the silicon substrate and the glass substrate is small. In
addition, the laminated substrate is obtained by, for example,
laminating together the glass substrate and the silicon substrate
while interposing a resin therebetween.
[0104] At this time, the resin thickness, the coefficient of
thermal expansion of resin, the heat treatment temperature at the
time of lamination together, etc. may affect warpage of the whole
laminated substrate. In the laminated substrate of one embodiment
of the present invention, the warpage of the whole laminated
substrate can be reduced by controlling the coefficient of thermal
expansion as in the above-described glass substrate according to
one embodiment of the present invention, so that the process margin
such as resin thickness, coefficient of thermal expansion of resin
and heat treatment temperature at the time of lamination together
can be broadened. In the laminated substrate of one embodiment of
the present invention, the glass substrate of the present invention
described above can be applied.
[0105] The method for manufacturing the glass substrate of one
embodiment of the present invention is described below. In the case
of manufacturing the glass substrate of one embodiment of the
present invention, the method includes a melting step of heating
glass raw materials to obtain a molten glass, a refining step of
removing bubbles from the molten glass, a forming step of forming
the molten glass into a sheet-like shape to obtain a glass ribbon,
and a slow cooling step of gradually cooling the glass ribbon to a
room temperature state.
[0106] In the melting step, raw materials are prepared so as to
afford a composition of the glass sheet obtained, and the raw
materials are continuously charged into a melting furnace and
heated preferably at approximately from 1,450 to 1,650.degree. C.
to obtain a molten glass.
[0107] As the raw material, for example, an oxide, a carbonate, a
nitrate, a hydroxide, and a halide such as chloride can be used. In
the case where the melting or refining step includes a step of
putting the molten glass into contact with platinum, a minute
platinum particle may dissolve out into the molten glass and be
mixed as an impurity in the glass sheet obtained, but use of a
nitrate raw material is effective in preventing the platinum
impurity from dissolving out.
[0108] As the nitrate, strontium nitrate, barium nitrate, magnesium
nitrate, calcium nitrate, etc. can be used. Use of strontium
nitrate is more preferred. As for the particle size of the raw
material, from a raw material having a large particle diameter of
several hundred microns to the extent of not causing an unmelted
residue to a raw material having a small particle diameter of about
several microns to the extent of causing no scattering during
transportation of raw materials and no aggregation as a secondary
particle can be appropriately used. A granulated form can also be
used. The moisture content of the raw material can also be
appropriately adjusted so as to prevent scattering of raw
materials. In addition, the melting conditions such as .beta.-OH
and oxidation-reduction degree or redox of Fe
[Fe.sup.2+/(Fe.sup.2++Fe.sup.3+)] can be appropriately adjusted and
used.
[0109] Next, the refining step is a step of removing bubbles from
the molten glass obtained in the above-described melting step. As
the refining step, a defoaming process by pressure reduction may be
applied. Furthermore, in the glass substrate in the present
invention, SO.sub.3 or SnO.sub.2 can be used as a refining agent.
As the SO.sub.3 source, a sulfate of at least one element selected
from Al, Mg, Ca, Sr, and Ba is preferred; a sulfate of an alkaline
earth metal is more preferred; and above all, CaSO.sub.4.2H.sub.2O,
SrSO.sub.4, and BaSO.sub.4 are still more preferred because of
their remarkable action of making the bubble large.
[0110] As the refining agent in the defoaming process by pressure
reduction, it is preferred to use a halogen such as Cl and F. As
the Cl source, a chloride of at least one element selected from Al,
Mg, Ca, Sr, and Ba is preferred; a chloride of an alkaline earth
metal is more preferred; and above all, SrCl.sub.2.6H.sub.2O and
BaCl.sub.2.2H.sub.2O are still more preferred because of their
remarkable action of making the bubble large and their small
deliquescency. As the F source, a fluoride of at least one element
selected from Al, Mg, Ca, Sr, and Ba is preferred; a fluoride of an
alkaline earth metal is more preferred; and above all, CaF.sub.2 is
still more preferred because of its remarkable action of increasing
the meltability of glass raw materials.
[0111] Next, the forming step is a step of forming the molten glass
deprived of bubbles in the refining step above into a sheet-like
shape to obtain a glass ribbon. As the forming step, for example, a
float process of flowing the molten glass on a molten metal and
thereby forming it into a sheet-like shape to obtain a glass ribbon
is applied.
[0112] Next, the slow cooling step is a step of gradually cooling
the glass ribbon obtained in the forming step above to a room
temperature state. In the slow cooling step, the glass ribbon is
gradually cooled to a room temperature state such that the average
cooling rate from a temperature at which the viscosity is 10.sup.13
dPas to a temperature at which the viscosity is 10.sup.1' dPas
becomes R. The gradually cooled glass ribbon is cut to obtain a
glass substrate.
[0113] In the method for manufacturing the glass substrate of one
embodiment of the present invention, the obtained glass substrate
has the following composition as represented by molar percentage
based on oxides:
[0114] SiO.sub.2: from 50% to 75%,
[0115] Al.sub.2O.sub.3: from 6% to 16%,
[0116] B.sub.2O.sub.3: from 0% to 15%,
[0117] MgO: from 0% to 15%,
[0118] CaO: from 0% to 13%,
[0119] SrO: from 0% to 11%,
[0120] BaO: from 0% to 9.5%, and
[0121] ZnO: from 0.1% to 10%.
[0122] In the method for manufacturing the glass substrate of one
embodiment of the present invention, the composition of the
obtained glass substrate and the average cooling rate R (unit:
.degree. C./min) from a temperature at which the viscosity of the
glass ribbon becomes 10.sup.13 dPas to a temperature at which the
viscosity becomes 10.sup.14.5 dPas in the slow cooling step satisfy
the following conditions (1) to (4).
0.0177.times.(content of SiO.sub.2)-0.0173.times.(content of
Al.sub.2O.sub.3)+0.0377.times.(content of
B.sub.2O.sub.3)+0.0771.times.(content of MgO)+0.1543.times.(content
of CaO)+0.1808.times.(content of SrO)+0.2082.times.(content of
BaO)+0.0396.times.(content of ZnO)+0.0344.times.log.sub.10 R is
from 2.70 to 3.20 Condition (1):
0.0181.times.(content of SiO.sub.2)+0.0004.times.(content of
Al.sub.2O.sub.3)+0.0387.times.(content of
B.sub.2O.sub.3)+0.0913.times.(content of MgO)+0.1621.times.(content
of CaO)+0.1900.times.(content of SrO)+0.2180.times.(content of
BaO)+0.0424.times.(content of ZnO)+0.0391.times.log.sub.10 R is
from 3.13 to 3.63 Condition (2):
0.0177.times.(content of SiO.sub.2)+0.0195.times.(content of
Al.sub.2O.sub.3)+0.0323.times.(content of
B.sub.2O.sub.3)+0.1015.times.(content of MgO)+0.1686.times.(content
of CaO)+0.1990.times.(content of SrO)+0.2179.times.(content of
BaO)+0.0493.times.(content of ZnO)+0.0312.times.log.sub.10 R is
from 3.45 to 3.95 Condition (3):
0.0111.times.(content of SiO.sub.2)+0.0250.times.(content of
Al.sub.2O.sub.3)+0.0078.times.(content of
B.sub.2O.sub.3)+0.0144.times.(content of MgO)+0.0053.times.(content
of CaO)+0.0052.times.(content of SrO)+0.0013.times.(content of
BaO)+0.0121.times.(content of ZnO)-0.0041.times.log.sub.10 R is
from 1.20 to 1.30 Condition (4):
[0123] The value represented by the formula (1) is preferably 2.80
or more, more preferably 2.90 or more. The value represented by the
formula (1) is preferably 3.10 or less, more preferably 3.00 or
less.
[0124] The value represented by the formula (2) is preferably 3.23
or more, more preferably 3.33 or more. The value represented by the
formula (2) is preferably 3.53 or less, more preferably 3.43 or
less.
[0125] The value represented by the formula (3) is preferably 3.55
or more, more preferably 3.65 or more. The value represented by the
formula (3) is preferably 3.85 or less, more preferably 3.75 or
less.
[0126] The value represented by the formula (4) is preferably 1.22
or more, more preferably 1.24 or more. The value represented by the
formula (4) is preferably 1.27 or less, more preferably 1.26 or
less.
[0127] When the values represented by the conditions (1) to (4) is
in the range above, the glass substrate having a reduced difference
in coefficient of thermal expansion from the silicon substrate can
be produced.
[0128] The present invention is not limited to the above-described
embodiments. Modifications, improvements, etc within the range
where the object of the present invention can be achieved are
included in the present invention.
[0129] For example, in the case of manufacturing the glass
substrate of one embodiment of the present invention, the molten
glass may be formed into a sheet-like shape by applying a fusion
process, a press forming process, etc. in the forming step.
[0130] Furthermore, in the case of manufacturing the glass
substrate of one embodiment of the present invention, a platinum
crucible may be used. In the case of using a platinum crucible, in
the melting step, raw materials are prepared to afford a
composition of the glass substrate obtained, a platinum crucible
containing the raw materials is charged into an electric furnace
and heated preferably at approximately from 1,450.degree. C. to
1,650.degree. C. A platinum stirrer is inserted, and stirring is
performed for 1 hour to 3 hours to obtain a molten glass.
[0131] In the forming step, the molten glass is cast on a carbon
plate and formed into a sheet-like shape. In the slow cooling step,
the sheet-like glass is gradually cooled to a room temperature
state and then cut to obtain a glass substrate.
[0132] The glass substrate obtained by cutting may be heated to,
for example, approximately Tg+50.degree. C. and then gradually
cooled to a room temperature state. The fictive viscosity .eta. can
thereby be adjusted.
Examples
[0133] The present invention is specifically described below by
referring to Examples, but the present invention is not limited to
these Examples.
[0134] Various glass raw materials such as silica sand were mixed
to afford a glass composition (target composition) shown in Table
1, and, as represented by molar percentage based on oxides, from
0.1% to 1% of a sulfate in terms of SO.sub.3, 0.16% of F, and 1% of
Cl were added per 100% of raw materials of the prepared target
composition. The raw materials were heated and melted with a
platinum crucible at a temperature of 1,550.degree. C. to
1,650.degree. C. for 3 hours. In the melting, a platinum stirrer
was put, and stirring was performed for 1 hour to achieve
homogenization of glass. The molten glass was cast on a carbon
plate and formed into a sheet-like shape, the sheet-like glass was
put in an electric furnace at a temperature of about Tg+50.degree.
C., and the electric furnace was subjected to temperature drop at a
cooling rate R (.degree. C./min) and cooled until the glass reached
room temperature.
[0135] The obtained glass was evaluated for the values determined
according to the following formulae (1) to (4), the average
coefficient of thermal expansion (unit: ppm/.degree. C.), the
density (unit: g/cm.sup.3), the Young's modulus (unit: GPa), and
the devitrification temperature (unit: .degree. C.). The results
are shown in Table 1, and the blank means the value was not
measured.
0.0177.times.(content of SiO.sub.2)-0.0173.times.(content of
Al.sub.2O.sub.3)+0.0377.times.(content of
B.sub.2O.sub.3)+0.0771.times.(content of MgO)+0.1543.times.(content
of CaO)+0.1808.times.(content of SrO)+0.2082.times.(content of
BaO)+0.0396.times.(content of ZnO)+0.0344.times.(12.3+log.sub.10
60-log.sub.10 .eta.) Formula (1):
0.0181.times.(content of SiO.sub.2)+0.0004.times.(content of
Al.sub.2O.sub.3)+0.0387.times.(content of
B.sub.2O.sub.3)+0.0913.times.(content of MgO)+0.1621.times.(content
of CaO)+0.1900.times.(content of SrO)+0.2180.times.(content of
BaO)+0.0424.times.(content of ZnO)+0.0391.times.(12.3+log.sub.10
60-log.sub.10 .eta.) Formula (2):
0.0177.times.(content of SiO.sub.2)+0.0195.times.(content of
Al.sub.2O.sub.3)+0.0323.times.(content of
B.sub.2O.sub.3)+0.1015.times.(content of MgO)+0.1686.times.(content
of CaO)+0.1990.times.(content of SrO)+0.2179.times.(content of
BaO)+0.0493.times.(content of ZnO)+0.0312.times.(12.3+log.sub.10
60-log.sub.10 .eta.) Formula (3):
0.0111.times.(content of SiO.sub.2)+0.0250.times.(content of
Al.sub.2O.sub.3)+0.0078.times.(content of
B.sub.2O.sub.3)+0.0144.times.(content of MgO)+0.0053.times.(content
of CaO)+0.0052.times.(content of SrO)+0.0013.times.(content of
BaO)+0.0121.times.(content of ZnO)-0.0041.times.(12.3+log.sub.10
60-log.sub.10 .eta.) Formula (4):
[0136] In the Tables, the values in parentheses are determined by
calculation. The residual amount of Fe.sub.2O.sub.3 in the glass
was from 50 ppm to 200 ppm as represented by mass ppm based on
oxides, and the residual amount of SO.sub.3 in the glass was from
10 ppm to 100 ppm as represented by mass ppm based on oxides.
Measurement methods of respective physical properties are described
below.
(Average Coefficient of Thermal Expansion)
[0137] The average coefficient of thermal expansion was measured
using a differential dilatometer (TMA) in accordance with the
method prescribed in JIS R3102 (1995). The measurement temperature
range is from 50 to 100.degree. C. for
.alpha..sub.50/.alpha..sub.100, from 100 to 200.degree. C. for
.alpha..sub.100/.alpha..sub.200, and from 200 to 300.degree. C. for
.alpha..sub.200/.alpha..sub.300.
[0138] Here, the average coefficient of thermal expansion of
single-crystal silicon was 2.94 ppm/.degree. C. at 50 to
100.degree. C., 3.37 ppm/.degree. C. at 100 to 200.degree. C., and
3.69 ppm/.degree. C. at 200 to 300.degree. C.
(Density)
[0139] About 20 g of a bubble-free glass block was measured by the
Archimedean method.
(Young's Modulus)
[0140] A glass having a thickness of 0.5 mm to 10 mm was measured
by the ultrasonic pulse method.
(Devitrification Temperature)
[0141] As for the devitrification temperature of the glass,
pulverized glass particles were put in a platinum-made dish and
heat-treated for 17 hours in an electric furnace controlled at a
given temperature, and an average value between a maximum
temperature causing precipitation of a crystal inside the glass and
a minimum temperature causing no precipitation of a crystal, which
were determined by observation with an optical microscope after the
heat treatment, was employed.
TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7
Ex. 8 Ex. 9 Ex. 10 Composition SiO.sub.2 66.8 66.8 66.0 66.0 66.8
65.0 66.1 55.4 67.2 65.1 (mol %) Al.sub.2O.sub.3 13.0 13.0 12.5
12.0 13.0 12.0 11.3 13.6 11.3 12.6 B.sub.2O.sub.3 4.6 4.6 4.5 7.0
4.6 4.5 7.8 6.1 10.0 6.0 MgO 5.0 8.0 5.0 3.0 7.3 4.0 5.1 23.0 4.6
4.0 CaO 6.6 4.6 6.0 5.0 6.6 5.0 4.5 0 5.5 1.5 SrO 1.0 1.0 2.0 1.5
1.0 1.4 5.2 0 0 1.5 BaO 0 0 0 2.0 0 1.1 0 0 1.4 3.7 ZnO 3.0 2.0 4.0
3.5 0.7 7.0 0.0 1.9 0.0 5.6 MgO + CaO + SrO + BaO + ZnO 15.6 15.6
17.0 15.0 15.6 18.5 14.8 24.9 11.5 16.3 Cooling rate R (.degree.
C./min) 40 100 1 1 40 1 40 1 1 1 Fictive viscosity log.sub.10.eta.
(dPa s) 12.5 12.1 14.1 14.1 12.5 14.1 12.5 14.1 14.1 14.1 Formula
(1) 2.89 2.79 2.95 3.05 2.98 2.95 3.36 2.82 2.86 2.96 Formula (2)
3.30 3.22 3.35 3.42 3.41 3.33 3.75 3.42 3.22 3.35 Formula (3) 3.60
3.53 3.67 3.68 3.72 3.64 4.01 3.87 3.43 3.63 Formula (4) 1.24 1.26
1.24 1.21 1.25 1.23 1.19 1.36 1.20 1.23 Average .alpha..sub.50/100
2.88 2.80 2.95 3.00 2.98 (2.95) 3.38 3.11 2.79 (2.96) coefficient
of .alpha..sub.100/200 3.26 3.16 3.33 3.37 3.36 (3.34) 3.75 3.64
3.14 (3.37) thermal .alpha..sub.200/300 3.58 3.48 3.67 3.69 3.73
(3.66) 4.02 4.09 3.38 (3.65) expansion
.alpha..sub.200/300/.alpha..sub.50/100 1.24 1.24 1.24 1.23 1.25
(1.24) 1.19 1.31 1.21 (1.23) Density (g/cm.sup.3) 2.51 2.49 2.55
2.55 2.48 2.62 2.51 (2.57) 2.41 2.65 Young's modulus (GPa) 84.0
85.3 85.6 79.2 84.6 84.4 76.0 (93.6) 74.6 80.4 Devitrification
Temperature (.degree. C.) 1315 1325 1310 1305 1300 1310 1270
1290
[0142] Examples 1 to 6 and 10 are present examples, and Examples 7
to 9 are comparative examples. In the glass substrates of Examples
1 to 6 and 10 which are present examples, the content of ZnO is
from 0.1% to 10% as represented by molar percentage based on
oxides, the average coefficient of thermal expansion
.alpha..sub.50/100 is from 2.70 ppm/.degree. C. to 3.20
ppm/.degree. C., the average coefficient of thermal expansion
.alpha..sub.200/300 is from 3.45 ppm/.degree. C. to 3.95
ppm/.degree. C., and the value
.alpha..sub.200/300/.alpha..sub.50/100 obtained by dividing the
average coefficient of thermal expansion .alpha..sub.200/300 at 200
to 300.degree. C. by the average coefficient of thermal expansion
.alpha..sub.50/100 at 50 to 100.degree. C. is from 1.20 to 1.30.
Consequently, in the heat treatment step of laminating together a
silicon substrate and a glass substrate, the residual strain
generated in the silicon substrate is likely to be small.
[0143] In the glass substrate of Examples 7 to 9, the range of any
one of the content of ZnO, .alpha..sub.50/100, .alpha..sub.200/300,
and .alpha..sub.200/300/.alpha..sub.50/100 deviates from the range
regarding the glass substrate in the present invention.
Consequently, in the heat treatment step of laminating together a
silicon substrate and a glass substrate, the residual strain
generated in the silicon substrate is likely to be large.
[0144] While the invention has been described in detail and with
reference to specific embodiments thereof, it will be apparent to
one skilled in the art that various changes and modifications can
be made therein without departing from the spirit and scope of the
invention. This application is based on Japanese Patent Application
(Patent Application No. 2016-154683) filed on Aug. 5, 2016, the
entirety of which is incorporated herein by way of reference. In
addition, all references cited herein are incorporated in their
entirety herein.
INDUSTRIAL APPLICABILITY
[0145] In the glass substrate of one embodiment of the present
invention, the difference in the coefficient of thermal expansion
from the silicon substrate is small, so that in the heat treatment
step of laminating together the glass substrate with the silicon
substrate and in the subsequent heat treatment step, generation of
residual strain attributable to the difference in the coefficient
of thermal expansion can be suppressed. Accordingly, the glass
substrate is suitable as a glass substrate for an image sensor such
as MEMS, CMOS or CIS, for which miniaturization of a device by
wafer-level packaging is effective.
[0146] In addition, the glass substrate is suitable as a cover
glass for a projection-use display device, for example, as a cover
glass of LCOS. For example, in LCOS or an image sensor, after
forming an electronic circuit on a silicon substrate, the cover
glass is adhered to the silicon substrate by using a resin or glass
frit as an adhesive material. The glass substrate according to the
present invention produces a small difference in the coefficient of
thermal expansion from the silicon substrate and therefore, the
stress generated on the adhesive interface when the temperature is
changed at the time of device manufacture or use is reduced. This
promises to reduce color unevenness attributable to photoelastic
deformation or enhance the long-term reliability.
[0147] Furthermore, the glass substrate of one embodiment of the
present invention is suitable as a hole-punched substrate of a
glass interposer (GIP) or as a support glass for semiconductor
backgrind. Moreover, the glass substrate of one embodiment of the
present invention can be suitably used for any application for the
glass substrate laminated together with a silicon substrate.
DESCRIPTION OF REFERENCE NUMERALS AND SIGNS
[0148] 10 Silicon substrate [0149] 20 Resin [0150] 30 Laminated
substrate [0151] G1 Glass substrate
* * * * *